Image storage apparatus



Sept# 3, 1957 J. T. MONANEY IMAGE STORAGE APPARATUS Filed Oct. 8, 1954Patented Sept. 3, 1957 nce strasse IMAGE sroanon Arran/aros JosephThomas McNaney, La Mesa, Calif., .assigrnn to General DynamicsCorporation, San Riego, Cailr., a corporation of Delaware ApplicationUctober 3, 1954, Seriai No. delgi??? 7 Claims. (Cl. S15-11) Thisinvention relates to image display apparatus and more particularly toimage display apparatus for storing and producing lasting imagedisplays.

In many computer, facsimile, and other electronic systems in whichoutput data is constantly changing, it has become increasingly necessarythat accurate retention of this output information at any given instantbe conveniently provided for extended periods of time. It is, therefore,an object of the present invention to provide apparatus for retainingand storing image information applied thereto at any given instant.

It is another object of the present invention to provide image storageapparatus adapted to simultaneously receive image information from aplurality of sources and produce sustained joint displays of the dataapplied at any given time.

It is another object of the present invention to provide image storageapparatus in the form of a cathoderay type storage tube having means forselectively erasing different images from the storage surface.

It is a further object of the present invention to pro-` vide alightweight, inexpensive image storage device utilizing simplifiedconstruction for producing lasting displays of a size suitable forsimultaneous presentation to a plurality of observers.

Other objects and features of the present invention will be readilyapparent toY those skilled in the art from the following specificationand appended drawings wherein is illustrated a preferred form of theinvention, and in which:

Figure 1 is a diagrammatic elevation View of a storage deviceillustrating an embodiment of the invention,

Figure 2 is a sectional view taken along line 2 2 of Figure 1,

Figure 3 is a fragmentary sectional View similar to Figure 2 butillustrating another embodiment of the invention,

Figure 4 is an enlarged sectional View taken along line 4--4 of Figure3,

Figure 5 is a fragmentary sectional View similar to Figure 3 butillustrating still another embodiment of the invention,

Figure 6 is a sectional View of a cathode-ray tube embodying theinvention, and

Figure 7 is an enlarged fragmentary view of a cathoderay tube screen,similar to that shown in Figure 6, but illustrating another embodimentof the invention.

In its preferred embodiments, the present invention basically comprisesa device having a plurality of layers including a radiation sensitivelayer which emits electrons in response to image radiations directed`thereon, an electron sensitive layer which responds to electronbombardment to produce image radiations in accordance with the electronimage patterns, and a screen which transforms the total emission of theradiation sensitive layer into a plurality of isolated and discreteelectron beams and also transforms the total radiations of the electronsensitive layer into a plurality of isolated and discrete radiationbeams. These laminae and the screen cooperate to produce area controlledradiation feedback from the electron sensitive lamina to the radiationsensitive lamina, such that electron emission is continuouslyregenerated from corresponding areas of electron sensitive lamina.

Referring to Figure 1, an image storage device is shown which includesan envelope 10 having a circular configuration in the particularconstruction illustrated. As illustrated in more detail in the sectionalview of Figure 2, a lamina of radiation sensitive material 11, a laminaof electron sensitive material 12, and a screen 13 having a plurality ofopenings therein are positioned within envelope 10. The particular shapeof envelope 10 forms no part of the present invention, and, as shown, itmay take the form of a circular cylinder 14 having end faces 15 and 15asuitably sealed thereto. Thus, cylinder 14 and end faces 15 and 15aprovide, in this embodiment, a sealed container capable of beingevacuated. End portions 15 and 15a are preferably transparent toradiation patterns directed thereon and, where these radiation patternsare in the form of light, transparent glass or plastic may be utilized.The cylindrical member 14 may be produced from materials similar tothose of end portions 15 and 15a, however, in some applications it maybe desirable to make member 14 non-transparent and thereby limitradiations to those directed through faces 15 or 15a.

Radiation sensitive material 11 serves to transform radiation t patternsdirected thereon into corresponding electron images. Although theutility of the present invention is not limited to light radiations, forpurposes of simplicity and clarification, the description hereafter willbe given in terms of light. Accordingly, radiation sensitive material 11may comprise material selected from the class of metals known asalkali-metals which characteristically emit electrons in the presence oflight. Typical metals of this class are lithium, sodium, potassium,ceasium, calcium, strontium, and the like. In accordance with theinvention one of these light sensitive materials is formed in acontinuous layer` 11, positioned and arranged within envelope 10 toreceive light patterns to be stored. A thin foil of the formed andeffectively installed within envelope 10 in juxtaposition withtransparent face 15 or, on the other hand, a lamina 11 of the propermaterial may be directly formed as a thin film upon face 15. Methods andtechniques of preparing this light sensitive, electron emissive surfaceare well known in the art and many references are available, such asTelevision by V. K. Zworykin and B. A. Morton published. in 1940 by JohnWiley and Sons, Inc. Consequently, a light pattern directed throughtransparent face 15 serves to energize light sensitive lamina 11whereupon lamina 11 emits electron streams in proportion to the lightintensity and thereupon transforms and reproduces the light pattern intoa corresponding integral electron image.

Screen 13 is positioned within envelope 19 and serves primarily tosubdivide the integral electron image produced by light sensitivesurface 11 into a plurality of independent elements to form a compositeimage in accordance with the integral image. Screen 13 may be asubstantially planar member or lamina formed of a nontransparentmaterial and is arranged to overlay portions of the continuous lightsensitive surface 11. As shown in greater detail in Figure 4, screen 13has incorporated therein a plurality of discrete areas or electronpervious portions 16, and with lamina 11 being a light sensitivematerial, screen 13 may be produced from opaque glass, plastic, ceramic,or like material in which areas 16 are actual Iopenings extendingtherethrough, which are generally normal to the surfaces. The screen1.3, which is opaque intermediate the areasV 16, is impervious to lighttransmission therethrough and may be said to be a light imperviousportion which has formed therethrough the areas or electron perviousportions 16,- Y Openings ,.16 are` of a size suicientto afford.passageways forfelectronV emission from surface 11` and` also'v toafford transmission therethrough of light from electron sensitiyematerial,12. Openings 16 may be formed in screen 13 by'any ofseveral`suitable methods, such as molding, drilling, or photoetching'.Y InFigure 2, screen 13 is adjacent the', continuous surface 1 1 and, asshown, is inV abutting relation thereto, The opaquersreenwithftsisolated transparent areas 16 serves ,to mask portions of thecontinuous., lightsensitive layer. 11, transforms the integral electronimage; into va composite imageformed within the areas.. 16 of. screen13, and openings. 16,1 communicating between laminae 11 and 172 provideseparatereg'enerative paths between corresponding areasY of saidlaminae; Screen 13 also serves toY restrict the directionjof travel'ofjthe resulting electron streams forming the;c ornpfosite imageV andconsequently 'restricts the area of regeneration. within limitsestablished` bythe 'respective transparent areas 16', `I-Ivence, with alight patterndirected through transparent face 15 and upon surface 11, acorrespond? ing integral4 electron imageV is produced.V Sleen, 13, inVassociationA with surface 11, breaks up the'integral` electronV imageinto aI plurality of independent image elements to form a compositeimage and channels. eahof the'particular image elements toward'predeterminedfareas onelectron'r'esponsive lamina12, y

`Itwill b e Vapparent'that the resolution of'thei composite` electronimage formed'by the totality of the independent electron streamsproduced by the openings 16 of screenillaw isdependent upon the numberof openings per unit area of the screen. openingsin screen 13resolutionwill be increased and the composite 'electron imagetransmitted through openings .i 16 will more nearly 4approximate-'theintegral electron` image formedV onsurfa.ce11. As shown in the sectionalview'oflFigure 4, apertures 16 arequite evenly distributed and arrangedthroughout the screen 13, however, the particularV arrangement of theapertures 16 forms no part of' thepresentlinvention andfromthe followingdescription it will become readily apparent to those skilled; in thearti lthat the size, arrangement, and distribution of the saperev turesmay be systematically organized for specific appli= cations. 'Forexample, itrmay be desired to utilize apertures of graduated sizes andthereby provide variations in, resolution over the surface of thescreen. Furthermore,

vit has been determinedlthat the pathlength travelled'by the pluralityoflelectron streams throughthe 'apertures I6. of screen 13isirnmater-ial tov theV operation of the device, however, the thicknessof -screenV 13 should be suingcient tovr withstand the requiredpotential4 gradients de A veloped` across.. it.

surface having actual openings therein, it shou-ldbe understood thatotherernbodi'ments ofthe screen are contemplated., For instance, screen13 may be in the form of amosaic plate comprising Vanmltiplicity oftransparent, nonconductive.. particles Visolatedj one fromfanother by anY Y opaque material. The resulting screen `is functionally similartojscreen 13 "illustrated in Figure`4and, when overlayi-ng,photoemissive surface 11, serves to convert the integral electron imageinto the. composite imageforrnedl by thefmultiplicity of independentelectronrstre'ams Which-- are transmitted to lamina 12Via the isolatednon-conductive-particles, The transparent. characteristic of the par`VVticlesuaffords'v a regenerative .feedbackI path from.- lamina.12vtog1aminav11lto thereby rte-energize exposed areasofthelightfsensitive surface. 11;

Y Referring Lto FigureZ, the laminal of electron sensitivematerial ;12,4which serves to convert 'electronibombard- Obviously, by increasing. the'number ofj' 4 1 is arranged to receive the various electron streamsforming the composite electr-on image. Y Inv terms of light, lamina 12may be produced from the generally used phosphors of zinc, cadmium, orcalcium which are commonly termed fluorescent materials. As in cathoderay tube applications, fluorescent layer 12 is continuous and may be inthe form of a thin llm or coating .which can be produced by the settlingout of the phosphor material from a water suspension by methods familiarto those skilled in the art. Electron sensitive lamina 12` is` arrangedadjacent' the transparent face 16 but may be formed directly upon face16 by the settling process or by usingV a volatile liquid such asacetone with a small amount of binder and spraying the electronsensitive material on surface 16. Electron sensitive layer 12 ispreferably coextensive with the apertured area yof screen 13 and, thus,with a light pattern directed upon surface 11 an electron image isproduced thereby which screen 13 subdivides into a multiplicity ofindependent electron streams corresponding to the image produced onsurface 11 and directs, each stream to a particular area on thefluorescent surface 12. Light is generated at surface 12 inresponsetothe electron bombardment. Inasmuch as openings` 16 allow thetransmission of light therethrough, as Wellas electron streams, thelight produced by a particular electron stream comprising the compositeimage is channeled backv to surface 1'1 through the same openingthroughwhich the energizing electron stream travelled. In this mannerregenerative feedback isy provided tore-excite the portion oftheVcontinuous surface llfwhich originally produced 'the elecf tron streamin response to an element ofthe incident lightA image. Since theelectron sensitive lamina. 12 is arranged adjacent the transparent endportion 16 of envelope '10, the 1 light image produced upon surface 12will be visiblet-V ductive layer 25 is connected to the voltageV divider22 by. a lea-d25. It will become apparent that means other,

- than conductive layer 25 may be utilized to Yestablish the*` field-between laminae 11 and 12. For example, where electron sensitive lamina12is aV goodconductive surface,

then the positive potential may be applied directlyVV thereto -by'connecting lead 25 `directly to lamina 12, However,

as. illustrated in Figure 2, conductive layer 24fis Varranged Vadjacentto and coextensive-with` the light sensi- `55 Although screen 13Sy has.been vdescribed iii-'terms offen tive layer 12. Layer 24 is 'npreferably a verythintrans-V parent coating or hlm of material suchas-silver, cadmiurm or aluminum, 'and the various electron streams whichmake. -up thercomposite electron image have-sufficientV energy to.penetrate. layerr24 and impinge Vuponv thelelecfV tron sensitive lamina12. Since layer 24 is transparent, the light. generated by` lamina 12also'penetrates layer` 24, passes through areas 16 in screen113;and1re-energizes the yassociated surface elements of'lamin-a 1I.Y"It, therefore, becomesV apparent that the presenceof 'conductivelayer24`.does.not adversely falfect the operation ofthe device. However,where layer 2'4--is utilized, its position with` respectto lamina. 12isimmateri-al and they may be transposed without materially affecting-theoperation-of;

thedevice. A

' in? operation, a light patternfis. directed-through trans-f parentface 15 and onto the light sensitive layer llvthereby Vcausing eachVincremental tareaV illuminated by the light upattern to produceanintegral `electron image which has la.pattern-andV density thatcorresponds in detail "to f the` pattern and density ofthe incidentlight-image. VThe electric field established across laminae 11 and 12serves to direct the integral electron image as a unit toward theelectron sensitive lamina 12. However, screen 13, as illustrated inFigure 2, is interposed between the layers and masks portions thereof.Hence, the integral electron image is dissected into a plurality ofindependent image elements by the configuration of screen 13 to form thecomposite electron image. Each of the plurality of discrete electron`beams forming the composite image has 1a magnitude proportional to theintensity ofthe light falling upon the corresponding area of layer 11underlying an opening 16 in screen 13. Each of the electron streamsflowing from layer 11 is confined within an opening 16 `of screen 13 andforms an element of the integral image generated at lamina 11 inresponse to the incident light image.

, The electric field applied to the electron beams travelling throughareas 16 in screen 13 imparts suiiicient venergy to the beams to causethem to penetrate coniductive layer 25 and impinge upon electronsensitive lamina 12. In response to bombardment lby the various electronstreams, area-s of lamina 12 in the path cof the streams are caused togenerate light--the intensity and pattern `of which is proportional tothe intensity and pattern of the respective electron beams. The areas oflight and shadow thus produced on lamina 12 -form a light image which isgenerally similar to the incident light pattern directed throughtransparent face 15 onto lamina 11. The light im-age produced on Vlamina12 is visible through transparent yface 16 `of envelope 10.

Regenerative action is established which serves to sus tain thesecondary light image developed on lamina 12. This regeneration isrealized by the feedback of light from lamina 12 through the transparentconductive layer 24 :and the openings 16 `of the collimating screen 13and onto the light sensitive layer 11. It, therefore, becomes 1apparentthat a plurality of regenerative feedback paths are provided and thelight from each element of the secondary light image is confined withinthe same `opening of screen 13 as that in which the correspondingelectron beam which produced the light was conned. The `electric fieldimpressed across laminae 11 and 12 may be utilized t-o control, ineffect, the degree of regeneration. .By varying the potential applied toconductive layer 24, control may be indirectly exerted `over the amountof light feedback to lamina 11 and lthis consequently providesregulation of the intensity of the light image displayed on surface 12and viewable by an 'observer through member 12.

In Figure 3 is illustrated a display device including light sensitivelayer 11, electron sensitive layer 12, and -screen 13 all of which arestructurally Iand operationally similar to those `describedhereinbefore. Elements 11, 12 and 13 are enclosed within an envelope 19awhich comprises transparent -faces 31 and 32 and an fannular member 33to which faces 31 and 32 may be suitably sealed. The `faces 31 and 32are preferably `constructed of a transparent material such as glass orplastic although other materials that Iare optically transparent may beused. Assuming that faces 31 and 32 are glass and lan electricallynon-conductive material, faces 31 and 32 are made electricallyconductive. The electrically conductive `coating applied to the glasssurface is also substantially transparent optically. A preferred methodof providing the transparent conductive lcoating is known as iridizingand is fully described in U. S. lPatent 2,522,531 entitled, Method ofProducing Electrically Conductive Coatings on Glass and -Mica Sheets.The unitary structure of transparent faces 31 and 32 comprising theglass surface and a transparent conductive layer of i-ridized tin iscommercially available and is generally known as electrically conductiveglass. Alternatively, transparent conductive faces 31 and 32 may includea glass surface and a conductive layer applied thereto by avacuum-evaporation process, such as a layer of evaporated aluminum, orlby a sputtering process, such as a layer of sputtered gold..

As shown, an electric field is established between faces 31 and 32 bydirect interconnection of source 21 through voltage divider 22 and leads23 and 2S to surfaces 31 and 32, Operation of the device illustrated inFigure 3 is similar to that described hereinbefore. A pattern of lightand shadow is directed through the transparent face 31 and vonto thelight sensitive member 11 whereby an integral electron image isgenerated which is proportional to the light and shadow of the incidentlight pattern. The voltage applied to the conductive faces 31 and 32from the source 21 yestablishes the electric field across the continuouslaminae 11 and 12 and serves to direct the integral electronic imagetoward lamina 12. Screen 13 is interposed between the laminae andoverlays portions -of each, hence, the integral electron image produced`on layer 11 is broken up into a multiplicity of independent imageelements in accordance with the opening 16 of screen 13. Each of theimage elements thereby produced has a magnitude proportional to theintensity lof the light 'falling upon the corresponding area of layer 11underlying the particular opening in the screen. As stated hereinbefore,the electric eld established between laminae 11 and 12 serves toaccelerate the various elements forming the composite image toward theelectron sensitive layer 12, and screen 13 with the electron perviousareas 16 therein serves not only to transform the integral electronimage into the elements forming the composite image but also aids inpreventing spreading and scattering of the electron image elements intraveling from lamina 11 to lamina 12. In response to bombardment by thevarious electron streams, areas of the continuous surface 12 in thepath-of the streams are caused to generate light. The light patterngenerated by lamina 12 in response to the independent electron streamsforming the composite image and channeled to the electron sensitivelamina 12 via the openings of screen 13 serves to reenergizecorresponding portions of surface 11. Energy feedback to lamina 11 isfocused by the openings 16 to the particular element of layer 11 fromwhich the energizing electron stream originally emanated. rfhis arearestricted feedback is regenerative and serves to produce a sustainedcomposite light image on layer 12 which may be viewed through thetransparent -end face 32.

As illustrated in Figure 5, a continuous light sensitive lamina11,-screen 34, and lamina of electron sensitive material 35 arepositioned within the envelope 10a, which includes transparentconductive faces 31 and 32 and the cylindrical member 33 suitablyconnected between the faces 31 and 32 to provide an enclosed container.A voltage is impressed across laminae 11 and. 35 by the connection `ofleads 23 and 25 to the conductive portion of transparent faces 31 and32. Thus, with a light pattern directed through end face 31 and onto thecontinuous light sensitive layer 11, an integral electron image isproduced by layer 11 which has a pattern corresponding in detail to theincident light pattern. Screen 34 is generally similar to screen 13described hereinbefore and illustrated in Figure 4 and is preferably aplanar member of non-transparent material which has a plurality of smallopenings therein, such -as the openings 16. The lamina ol' electronsensitive material 35, which serves to transform electron images intolight, may comprise one of the fluorescent materials mentionedhereinbefore, however, in this display device the fluorescent lamina 3Sis arranged within the openings of screen 34. Thus, it becomes apparentthat within screen 34, lamina 35 is a discontinuous layer and is more inthe form of isolated islands of electron sensitive material surroundedby the opaque areas of screen 34 and together the screen and fluorescentmate rial constitute a continuous layer. The electron sensitive materialmay be established within the openings of screen 34 by the well knownprocess of settling out of the phosphor material from a watersuspension. Screen 34 is arranged adjacent the continuous lightsensitive surface 11,

` tivematerial-withirrrthe-V openings oli/screen 34 andlight' generatedby-loneelementl oflami'n-a `35Jis. channelled by the Vsurrounding opaqueportions of screen- 34 to a partieular incremental,areaofsurfacelll. Itbecomes apparentdy at'tlie--Tfeedbacsk fr'om elements of fluorescentlayer 135f`to`associated areas'yoflayer 1-1 isl regenerative. This-areacontrolled regenerative feedback serves to producea sustainedl compositelight? image onlayer 35, and being arranged adjacent the, transparentAend' portion 32 of' envelope 10a, the light image produced thereon willv bevisibleto an observer. Although envelope a is illustrated in thedrawings and' describedv in detail in conjunction-with the` descriptionandoperation of lamina 11, screen; 34, andi electron sensitive lamina35, shown in Figurer 5, it 'is understood that envelope 10 and suitablemeans for impressing the voltage across Ithe laminae as shown'anddescribed in connection with Figure 2 may be el'ectivelylutilized. Y

VReferring now-to Figure 6 a cathode ray type image storage"devicerisillustrated which includes an evacuated envelope '40?enclosingafstorage screen 41 to be described in detail hereinafter, anelectron gun 42 for generating, focusing, and' accelerating af beam ofelectrons toward causing the electron'beam tobe deilected to variousareas ofscreen41. Y Y V,

' Theelectron gun 42 positioned atan end of envelope 40' preferablycomprises a cathode 44, a control electrode 45; Iand an acceleratinganode 46. Associated with electron gunV 42 and positioned along the pathof the electron beam isthe set of deection plates 43. For purposes ofsimpli'cation a` single 'pair of deflection plates is illustrated whichwill serve tov deflect the electron beam in a-singl'e plane upon areasof storage screen 41, however, it will' be apparent that Ian additionalpair of deection plates may be incorporated toV provide deflections -ofthe electron-"beam in a plane normal to that afforded by the platesillustrated. Thus, in response to 4signals lapplied to 4both pairs ofdeflection plates 43, the `electron beam maybe directed to any. desiredarea fon storage screen 41. -An anode4'7 is positioned-betweendeflection plates 4'3 andstorage'screen-41 and serves both to acceleratethe yelectron .beam and to collectphotoelectrons gene-rated byelementsofV the lstorage screen41 under conditions toV bedescribeldin'detail hereinafter. The particular contiguration=ofanode 47forms nopart'ofthe present invention and may 'bei conveniently embodiedas a conductive wall-:coating on the inside of'tubc envelope 46,

"Storage screen 41 is' positioned within the evacuated envelope 40 and'inthe path of the electron lbea-m generated'by'electron gunr42. Intheembodiment illustrated in Figure 6V screen 41 includes a layer-of'.light sensitive material '11; a layer of electron sensitive material 12,and a' screen 13 interposed between said laminae. Screen 134 'hasvopenings 16 therein which provide independent vpassageways for bothelectron streamsemitted from `surface 11 .and light radiation producedfrom electron sensitive material 12; Storage screen 41 may also include.a pair of transparent, conductive layers 48 `and 49 which arepositioned adjacent. the layersv 11 and 12, respectively,

Y and ,serve 'to apply-Yacceleratingvoltages thereacross.

Storage screenAL may alsortzomplise;ailarninazofelectron Ystorage-screen41, and a set Iofgdellection plates 43 for Y sensitive material 501`arrangedlm todi-rectly receive; elec-i tron 'images Aformedfby:theincident electron e-bearnL gene erated by-guny `42," and" transformsaid-electronimages into?.A

corresponding; -lightimages.V v

Meansiirthe forni-ofa voltage divider, :referred itoA generally byreference numeral 52, Y is 'connectedV acrossA a; sourceoffdirect;currentI voltage (not show-n) and'serves to Aprovide; suitableelectric eldsacross lamina 11, and; lamina. 12, as-wellas maintainingthe'various electrodes, such-as-anode747f and the elementsl ofthe,VVelectron gunk 42, at their proper operatingfvoltage levels.-V idivider-'52 includes droppingresistorswSS through 579 and with theysource Yofj Voltage connected with proper ,polarity` acrosslthefterminals indicated-F and' the voltage apj-f Y pliedtoconductive layerA49-by lead 61,'under normal:

operating conditions, willfbe Vmaintainedlat apositive potential withlrespect to the Voltage applied to the'c'onduc-.

tive layer V48 by lead 62; `Hence,V thenvoltage appliedV across laminae11`v and V12 is' the voltage drop appearing across resistor 54. Throughlconnection by `lead 63; to. the junction of dropping resistorsY 55 Vand56, suitable..

operating voltageis afforded anode 47, .and under normal' operatingconditions anode"47ismaintained ata voltage level lower than either'thevoltagejapplied' to lamina 1'1 or laminalZ. 4Theelements of electron gun52 are main,-V tainedat suitable operating potentials by. beingconnected; as shown, across droppingresistorsSS and 59 ofnetwork 52: y

A'lead 6,4'isv connected'` to controlY grid 45 ofY electron gunHand-provides means for applying,V an intensityrsignal thereto. which`serves to trigger the electron, beam generated by cathode v44' oirAanden.V Leads 6,5 and66 areonnectedjto the deflection pilates 43' andprovidev meanspfor applying signals. thereto whereby `the electronVbearnngenerated by gun'42is. selectively: directed overdifferent areaslof'storage screen 41,.

'j In, operation with a suitable energizing si'gnal'applied` overVlead"`6`4'l to control electrode 45, an electron beam is generated bycathode 44 avndj,directed/along,the,axis;VV

ofienvelope` toward'the storage screen-41, In travel'- ling .towardscreen'41, theV electron beamis directed betweenV deflection plates 43.By the application of signals to deflection plates 43v via leads 65 andV66, the electron beam may be selectively directed to dierent areas fonscreen 41, andby well' known circuits the beam maybe A caused jto besscanned, if desired, across the storage screen 41' in ,anyVdesiredraster. Y V

Directedl toward storage screen 41,' the electron beam strikes .theelectron sensitive layer with suflici'ent energy i to cause it toVgenerate a light image in accordance withl lzinc, cadmium, or calcium.lWhere utilized in association witharelativelylow energy electron beam,layer 50'serves top'adapt the-essential storage elements ofV the storagescreen 41 to cathode ray tube applications`, and itV will becomeapparent to those skilledin 'the art thatlamina '50i is noti essentialin cathode ray storage tubes wherein high energy Acathode raybeams areutilized.' 'In these` latterfapplication's, the `high energy.electronfbeam possesses sulicientenergy-to'penetrate layer 48 andlayer`11,

traverse; the openings '16,V in screeng13and kstrike the;electronsensitivev layerI 12, whereupon 4a light image is generatedinracoordance with the incident electron image formedbylthe beam;However, for purposesof claritication, uoitescentllamina, 50'isincorporated in the-embodimentfillustratedin Figure and theVlight'images t' formed'thereon Vin response to bombardmentby the elec-Vtr'on `beam, pass through the transparent conductive layer 48'andvstrike light sensitive layerll; V Conductive layerV 48- is similar tovconductive Vlayerj24,.

described in connection with` Figure 2 andV ils'spreferably' 7 5asverytthin., transparent cating offmaterial," such-'as alu- Voltageminum.Y As illustrated in Figure 6, the transparent` tinuous layer andgenerates an integral electron image,v

corresponding in detail to an electron image directed upon layer 50 bythe cathode ray beam. Screen 13 is positioned adjacent the lightsensitive layer 11 and serves primarily to subdivide the integralelectron image produced on surface 11 `into a plurality of independentelements which together form a composite image in accordance with theintegral electron image. Screen 13 is structurally and functionallysimilar to the screen 13 shown in detail in Figure 4. As described,screen 13 is preferably a planar member, or lamina, of opaque materialwhich is arranged to overlay and mask portions of the continuous lightsensitive surface 11. Screen 13, with openings 16 therein, not onlydissects the integral electron image formed on surface 11 into theindependent elements of the composite image, but also serves to restrictthe direction of travel of the resulting electron streams andconsequently proi vides separate channels for each of the compositeimage elements directed toward the electron responsive lamina 12.

Under normal operating conditions, the electric fields applied betweenlaminae 11 and 12 produce forces on the resulting electron streams whichaccelerate the bundle of streams through the channels formed by openings16 toward electron responsive lamina 12. Lamina 12, which serves toconvert electron bombardment into corresponding light patterns, is athin film or coating functionally similar to layer 50 and may besimilarly produced from any of the fluorescent materials mentionedhereinbefore. Hence, in response to bombardment by the electron streams,light elements are generated by lamina 12 which correspond to theelectron elements forming the composite electron image, and theaggregate of the light elements produce an image corresponding to thecomposite electron image formed on the surface of lamina 11 adjacentscreen 13. It, therefore, becomes` apparent that each element of thelight image produced on lamina 12 is energized by an electron streamderived from an area of surface 11 which lies beneath the opening inscreen 13 associated with the particular incremental area of lamina 12which produced the light element. j

The light image formed upon lamina 12 by the individual light elementsmay be made visible through the transparent conductive layer 49 and atransparent end face 67 of envelope 40, As described hereinbefore, theimage displayed on lamina 12 is sustained thereon through rep generativefeedback of light to iiuorescent lamina 11. A plurality of independentregenerative feedback paths between laminae 12 and 11 are provided bythe openings in screen 13, which is interposed between the laminae.Light t from each element of the image appearing on lamina 12v ischannelled back to lamina 11 through the same opening in screen 13 inwhich the particularenergizing electron stream travelled in producingthe particular light element. Thus, elements forming the light patterngenerated by lamina 12 in response to the electron streams forming thecomposite electron image, serve to re-energize the areas of surface 11that originally produced the light element and in this manner the imagedescribed on lamina 50 by the electron beam produced by electron gun 42is stored as a corresponding image visible through the end face 67 ofthe cathode ray tube.

The cathode ray display and storage device also includes circuit means71 for selectively removing different retained images from storagescreen 41. Circuit means 71 is associated with the elements of thevoltage divider 52, which serves to establish predetermined electricfields between the light sensitive lamina 11, electron sensitive lamina12, and anode 47 for retaining the images produced by the cathode raybeam, and in addition to essential components described in connectionwith voltage divider network 52 includes an electron tube 72 having ananode 73, a cathode 74, and a control electrode 75. Anode 73 may beconnected directly to terminal of voltage divider 52 and the anodecircuit is completed by connecting cathode 74 through a resistor 76 tothe junction between dropping resistors 5S and 56 of divider 52. A gridreturn resistor 77 is provided, which is connected between an inputterminal 78 and the junction of control grid 75 and a second inputterminal 79. Thus, it may be seen that electron tube 72, with itsassociated components is actually in parallel with dropping resistor 55and functions to selectively control the voltage applied to anode 47over a voltage range sutlicient to permit storage and image display orselective erasure of previously stored images in response to externalsignals.

Under operating conditions for writing, displaying, and storing animage, electron tube 72 is non-conductive and voltages are establishedby voltage divider 52 and applied to elements of the cathode ray tubewhich maintain anode 47 at a voltage level lower than either the voltageapplied to lamina 11 or lamina 12. For descriptive purposes, it may beassumed that to establish the aforementioned normal operatingconditions, the values: of the various dropping resistors are so chosenthat a potential of 10,000 volts appears at terminal a potential of9,000 volts is established at the junction of resistors 53 and 54, andapotential of 8,000 volts is established at the junction of resistors 55and 56. When it is desired to erase a previously stored image or aportion thereof a signal voltage is applied to control electrode 45 overlead 64 which serves to turn the electron beam on. By the application ofsuitable deection signals applied to the deilection plates 43 over theleads 65 and 66, the electron beam is then directed to the area of thestorage screen 41 tol be erased. To actually initiate erasure of theimage, an external selective erase signal is applied to electron tube 72through input terminals 78 and 79. Electron tube 72 is thereby driven tobecome conductive whereupon dropping resistor 5S is essentially shortcircuited. Thus, the junction between resistors 55 and 56 is raised to avoltage level approximating the assumed 10,000 volts applied to terminalof voltage divider network 52. Under these conditions and withaccelerating anode 47 interconnected by lead 63 to the junction ofresistors 55 and 56, the voltage applied to anode 47 is raised toapproximately 10,000 volts and to a voltage level substantially higherthan either the voltage applied to lamina 11 or lamina 12. Hence,electron emission from lamina 11 is now directed toward anode 47 as aresult of the potential gradient appearing therebetween and electronemission is materially reduced in a direction toward lamina 12. Thisaction reduces the electron iiow from lamina 11 to lamina 12 below thecritical point necessary to energize iiuorescent lamina 12. and therebyremoves this portion of the image. Anode 47 will remain at a positivevoltage level with respect to both laminae 11 and 12 during the periodthe external selective erase signal is applied to the input terminals land 79 of tube 72, and upon removal of this signal, anode 47 is restoredto its normal Voltage level and the device is returned to its normaloperating conditions for Writing, storing, and displaying an image.

Where a high energy electron beam is produced by the cathode ray tube,the fluorescent layer 50 may be eliminated and the device will functionin generally the same manner. The ability of an electron beam topenetrate thin conductive layers, such as conductive layers 48 and 49,is well known and the incident electron beam generatedby-electron gun'42 and `directedupon'tlle storage .i

screen` penetrates lightsensitive Vlayerpllfasvvellasconductilvelayer'48,Y passes through theopenings 176of`scree'n13; andl impinges upon electron sensitive lamina 12.' Light produced'bylamina 1'2"is1directed,` back to lamina 11'.' and is localized' by theopeningsin screenluto'those areas oflamina 11 underlying' theilluminatedv openings ofthe.` screen. jllluminationof larninallv causesphotoelect'rons. Y to -be generated 'in proportion to" theimpinging,lightpand` these photoeliectrons are directed through the sameopen- A modification' of the storagescreen `shown.in Figureg-isillfustrated in Figure 7 and includes a continuousllight sensitivelamina 11, Va screen 81having a plurality 'of openings therein, and alamina of electronV sensitive material 82 which is` arranged within theopenings-of screen 81. An electric field'is impressed across lamina 11and the elements comprising lamina 82 by the leads61 and `62'which.

.are interconnected between the voltage divider SZ' described inconnection with Figure 6, and to conductive.

endface `253 and directlyto the continuous light sensitive lamina 11',respectively. Lead 63 serves, to interconnect the accelerating anode 47with the'junction of'dropping resistors 55' and 56'and thereby'suppliesboth the normal f storage potentials andselective erase potentialsthereto. Transparent conductive end face 83' is provided which mayv beyfabricated from` electrically conductive. glass produced by methodsreferred to hereinbefore and' issuit-V v ably sealed to envelope S4.

zjsoasad produced Vby the u-orescent materialV arrangedjirrtliejIopenings of screen 81 serves to energize adjacent por? Y leads '61'and62, Hence, conductive layers-48"an'd 49 v Y illustrated in Figure ,6also may be effectively eliminated.

Screen 81 is generally physically andV functionally simi-. i

larito screen 13 described hereinbefore and illustratedin Figure 4and ispreferably a planar member of non-transparent material which has aplurality of'small openings. therein in the orderof affew thousandths ofanv inch, such as openings 16. Fluorescent phosphor material 82;A whichserves to transform electron images into 1ight,.is arranged withintheopenings. by, for example, a settling process. Thusjtogether the'screen81 and the iluorescent material 82' form a surface ofisolated elemen-tsof electron .sensiofthe screen. Y Screen.81` with the areas of.uo'rescentmaterial thereinis interposed betweenthe electricallyconductive glass surfacev 83V andlthe continuous light` sensitivesurface V11; The opaque portions ofscreen 8 1"k serve to mask outportions of laminall and prevent 'diffusion and.

written'by the beam thereupon is transformed into plu-... rality `of.independent light elements, the sum of which.

correspond to the incident electron image. The ilight tions ofthecontinuous-light 'sensitive lamina 11,V rIhe re- 'sulti'ng electronimageV thereby producedV on laminaVT 11 serves to relenergize thecorresponding adjacent elements o of lluorescentmaterial S2interposediin the nonftrans.-

` parent :screen 81. A.This regenerative actionproducesthe n desired.retention of theimage. written by the electron Y beam generated` by thecathode ray tube which maybe readily viewed through the transparent endface S3.

Y i It will; be apparent tlratselective erasure ofthe entire image, 4orany portion thereof, maybe accompli-shed in the mannerv describedhereinbefore. in connection Awith Figure. 6'.Y By the application `of "a"selective erasesignalA to. input terminals 78 and 79V of electron tube72 associfV ated withV voltage divider 52, anode. 47 Vis' switched4 to.aj Vvoltage level which is higher thaneither that applied tonv lamina11 or, conductive face8`3 whereupon thelimage o underlying thearea of..the screen to which the incident Velectro'nvbeam is directed is removed.o l While'certain preferred embodiments of .the invention Y have beenspecically disclosed, it is understoodthat the invention is not VlimitedtheretoV las many variations will be readily apparent to those skilledin the art,=and the invention is to be givenoits broadest possibleinterpretation within the terms of the following claims:v v

What I"claim is: A Y

ll. In .an image storage device including a laminar electronnsensitivematerial yarranged to receive electron image emission and transformsaidimage Vemission into corre- Y splondinglight radiation patterns, alaminar light radiation sensitive material adapted to causetransformationof light radiation patterns-into corresponding electronimage emission, said image emission beingdirected toward said elec-vtron'sensitivemat-erial; at least one of saidlaminae being Y Y acontinuous surface, the improvement Icomprising a screen having at leastyone light -transparent electron perviousvA portion andat least onenon-conductive light impervious portion, said. screen being interposed'adjacent saidlaminae and arranged to overlay said continuous surface,-`said electronpervious portion being adapted to pass electronV tivematerial completely surrounded by the opaque areas scattering of'li'ghtfrom the individuali areas of''uorescent l material. K Y

,Under operating |conditions for writing and storing an image, voltageconditions developed 'by voltage divider 52' 'and' applied over theleads 61, 62 and 63 establish the conductive surface 33 at a voltageapplied to ac-celerat- Ving anode 47 at a voltage level lower than thatapplied- Vto lamina 11. Thefelectron beam produced 'by the electron gunof' the cathodelray. tube and directed toward vthe storage screen has'sufficient `energy Vto penetrate photo-V cathode :.11 andimpinge'directly upon the surface formedl by the screen 81 and 'theisolated areas ofiluorescent'vv material 82 i formed Withinthe screen; iThe areas` of fluorescent material 82. which are bombardedf'bythe-electronfbeam generate light ypatterns in accordance -withi'thepatternl described by the incident electronbeam. Howg Vever, with-'theconfiguration of the opaquescre'en '815 andVY uorescenti'areassvSZ4asdescribedjtheelectronimager` "emission therethrough andsaid imperviousportion being,V

adapted to isolate light radiation from saidrelectron sensi`tivematerial, said screen being adapted to provide improvedregenerationover limitedV areas of said laminaef 2. In an. image storage deviceincluding a laminay of "electron sensitivejmaterial arranged to receiveelectron image emission and transforml said image emissionlintocorresponding light radiationl patterns, ala-mina of light v radiationsensitive material adapted' to Icause transformation of'lightiadiationpatterns into'corresponding electron image emission; said image emissionbeingdirected toward said. electr-on sensitiv-ematerial, at least one;of

saidrlaminae. beingY al continuous surface, the improve-V mentcomprising a screen having Ia plurality 4of light transf parent electronperviou's portions and a plurality of non- Aconductive light imperviousportions, saidscreen being interposed adjacent said laminae and'arranged to'overlay saidl 'continuoussurfacd said electron perviousportions lbeing 'adaptedito pass electron emission therethrough and,.said imperviousportions beingadaptedto isolate lightV radiationfromsa-id electron sensitive material, said screen Y regeneration. overbeing adapted .to provide improved limited areas of said lamin'ae.

' 3; An4 evacuatedx image. srt-orage device oomprisingfin". combination1a lamlnar electron-,sensitive material adapted* .to receive .electronimageemission'a'nd transform said image emission into correspondinglightradiation patterns, Va laminar photo emissivematerial capable o freceiving said light radiation patterns andtrausformingsaid patterns.into corresponding electron image emission, said 75 image' emissionbeing'directed 'toward 4said electron Isensitive material, at least oneof said laminae being a continuous surface, and a screen having a lighttransparent electron pervious portion and a non-conductive lightimpervious portion, said screen being interposed adjacent said laminaeand arranged to overlay said continuous surface, said pervious portionbeing adapted to pass said image emission, said impervious portion beingadapted to isolate light radiation from said electron sensitivematerial, said screen being adapted to provide improved regenerationover limited areas of said laminae.

4. An evacuated image storage device comprising in combination a laminarelectron sensitive material adapted to receive electron image emissionand transform said image emission into corresponding light radiationpatterns, la laminar photo emissive material capable of receiving saidlight radiation patterns and transforming said patterns intocorresponding electron image emission, said image emission beingdirected toward said electron sensitive material, at least one of saidlaminae 'being a continuous surface, and a screen having a lighttransparent electron pervious portion and a non-conductive lightimpervious portion, said screen being interposed ladjacent said laminaeand arranged to overlay said continuous surface, said pervious portionbeing adapted to selectively accept and pass said image emission, saidimpervious portion being adapted to isolate light radiation from saidelectron sensitive material, said screen being adapted to provideimproved regeneration over limited areas of said laminae, and means forestablishing an electric field between said laminae, said means being`adapted to cause acceleration of said image emission toward saidelectron sensitive material.

5. An evacuated image storage device comprising in combination a laminarelectron sensitive material adapted to receive electron image emissionand transform said image emission into corresponding light radiationpatterns, a laminar photo emissive material capable of receiving saidlight radiation patterns and transforming said patterns intocorresponding electron image emission, said image emission beingdirected toward said electron sensitive material, at least one of saidlaminae being a continnous surface, and a screen having a lighttransparent electron pervious portion and a non-conductive lightimpervious portion, said screen being interposed adjacent said laminaeand arranged to overlay said continuous surface, said pervious portionbeing adapted to pass said image emission, said impervious portion beingadapted to isolate `light radiation from said electron sensitivematerial, said screen being adapted to provide improved regenerationover limited areas of said laminae, said electron sensitive materialbeing disposed within at least a portion of said electron perviousportion, and means for establishing an electric field between saidlaminae of materials, said means being adapted to cause acceleration ofsaid image emission toward said electron sensitive material.

6. In a cathode ray device including means for producing and directing ahigh energy electron beam emission along said device including anaccelerating anode, a storage screen positioned within the device in thepath of said beam emission, said storage screen including a firstlaminar electron sensitive material adapted to transform said beamemission into corresponding light images, a laminar light sensitivematerial arranged to convert said light images into correspondingelectron image emission, a second laminar electron sensitive materialadapted to transform said image emission in corresponding light images,said image emission being directed toward said second electron sensitivematerial, at least one of said latter two laminae being a continuoussurface, and a screen having light transparent electron perviousportions and non-conductive light impervious portions, said screen beinginterposed adjacent said latter two laminae and arranged to overlay saidcontinuous surface, said pervious portion being adapted to pass saidimage emission, said impervious portion being adapted to isolate lightradiation from said electron sensitive material, said screen beingadapted to provide improved regeneration over limited areas of saidlatter two laminae, means for establishing predetermined electric fieldsbetween said light sensitive material, said second electron sensitivematerial and said accelerating anode to provide retention of saidimages, said means including a circuit arranged to change said retainingfields for selectively removing retained images from the screen.

7. In a cathode ray device including means for producing and directing ahigh energy electron beam emission along said device including anaccelerating anode, a storage screen positioned within the device in thepath of said beam emission, said storage screen including a laminarlight sensitive material capable of converting light images intocorresponding electron image emission, a laminar electron sensitivematerial adapted to selectively transform said electron beam emissionand said image emission into corresponding said light images, said imageemission being directed toward said electron sensitive material, atleast one of said laminae being a continuous surface, and a screenhaving light transparent electron pervious portions and non-conductivelight impervious portions, said screen being interposed adjacent saidlaminae and arranged to overlay said continuous surface, said perviousportion being adapted to selectively accept and pass said imageemission, said electron sensitive material being disposed within atleast a portion of said pervious portion, said impervious portion beingadapted to isolate light radiation from said electron sensitivematerial, said screen being adapted to provide improved regenerationover limited areas of said laminae, means for establishing predeterminedelectric fields between said light sensitive material, said electronsensitive material and said accelerating anode to provide retention ofsaid images, said means including a circuit arranged to change saidretaining lelds for selectively removing retained images from thescreen.

References Cited in the tile of this patent UNITED STATES PATENTS Re.23,802 Sheldon Mar. 16, 1954 2,594,740 DeForest et al Apr. 29, 19522,605,335 Greenwood et al J'uly 29, 1952 2,683,832 Edwards et alJuly-13, 1954 2,699,511 Sheldon Ian. 11, 1955 2,773,992 Ullery Dec. 11,1956

